Oscar De La Hoya Slams Trump's Taco Salad

Oscar De La Hoya isn't impressed with Donald Trump's taco salad tribute to Cinco de Mayo.

The boxer just joined the guys on "TMZ Sports" (airs Thursday on FS1) -- and addressed not only the taco salad situation ... but also the new footage of him praising Trump's golf skills.

Here's a teaser of the interview -- which airs tonight on FS1.

Oscar makes it clear he's not backing off his "Trump Is a Cheater" golf stance ... and has a huge problem with his taco salad.

Watch TMZ Sports -- weeknights at 9 PM PT on FS1.